Metal punching devices, particularly sheet metal punching devices, frequently utilize punching tools which are carried by punch guide assemblies. Stripping devices such as stripper plates are often used in association with such punching tools to ensure that punched material is stripped from the punch tip. It is desirable, in certain punching applications, to facilitate the installation and removal of different punching tools having varying shapes within a single guide assembly.
One known way of retaining a stripper plate to a guide assembly is with the use of a wire split locking ring and screw combination, as disclosed in U.S. Pat. No. 4,446,767. In this device, the operator places the stripper plate inside the guide assembly, and then compresses the split locking-ring while seating the ring in a groove inside the guide assembly. Once the ring is seated into the groove, the operator uses a wrench to install a special screw between the two ends of the locking ring. If the locking ring is not seated correctly, the ring and stripper plate are susceptible to dislodging from the guide assembly during operation of the punch, with a potential for damage to the tool and to the punching machine. In order to remove the stripper plate, the installation process is reversed.
Another known alternative is one employed by Cole Engineered Tools (C. P. E. Tooling, Inc.). This design includes a stripper plate retaining device using a machined pocket and a ball detent as a rough locator of the stripper plate. The punch is lowered into the stripper plate, and actually holds the stripper in the pocket. In this device, the punch must first be removed in order to install or remove the stripper plate. Depending on the tool design for removing the punch from the stripper plate, this usually entails at least partial disassembly of the guide assembly.
It is therefore apparent that there exists a need for a device that will provide quick and easy removal and installation of a stripper plate on a punch guide assembly, which also provides a positive locking mechanism to assure stripper plate retention during use.